1. Field of the Invention
The present invention relates to a data transferring apparatus for transferring liquid ejection data and a liquid ejecting apparatus of liquid ejection data for transferring the liquid ejection data to a liquid ejecting head, wherein the liquid ejection data is inputted into the liquid ejecting apparatus which ejects a liquid such as ink from the liquid ejecting head onto a medium to be ejected.
2. Description of the Related Art
A liquid ejecting apparatus called an inkjet type printer ink records image data by ejecting ink from a recording head onto recording papers. The inkjet type printer ejects ink droplets of plural colors from plural nozzle arrays which are provided at the head face of the recording head as developing image data, which has been compressed to be capable of being developed in line, to bitmap images in line and forming the developed bitmap images on the recording side of the recording papers. It forms images on the recording papers by ejecting ink droplets of plural colors to form plural ink dots. Further, the compressed data capable of being developed in line is, for example, the compressed data by the run length compression method which is generally widely known, capable of developing per byte unit sequentially.
This inkjet type recording apparatus generally includes a data transferring apparatus for receiving image data compressed to be capable of being developed in line inputted from an external apparatus such as a personal computer, developing (extracting) the inputted compressed data inline, performing data processes required for the developed bitmap images and then transferring the data to a register of the recording head. The generally conventional data transferring apparatus is configured, for example, as shown in FIG. 12.
The data transferring apparatus 10 has a system bus SB as a data transfer route. To the system bus SB a microprocessor (MPU) 11, a RAM 12 and a head controlling unit 13 are coupled so as to transfer data, and a recording head 62 is coupled to the head controlling unit 13. The compressed recording data transferred from an information processing apparatus such as a personal computer or a digital camera, which is not shown in drawings, is stored in the RAM 12 via the system bus SB.
The compressed recording data stored in a compressed data storing area of the RAM 12 is transferred to the microprocessor 11 via the system bus SB one byte each in order (a route represented by the symbol A), extracted by a program in accordance with an extraction sequence one byte each in order, then transferred to the RAM 12 via the system bus SB one byte each in order once more (a route represented by the symbol B) and then stored a desired bitmap image area of the RAM 12. When the developed data has been completely stored in the bitmap image area of the RAM 12, the developed data in the bitmap image area of the RAM 12 is transferred to a register (not shown in drawings) in the head controlling unit 13 via the system bus SB one byte each (a route represented by the symbol C) and ink is ejected from each of the nozzle arrays of the recording head 62 onto the recording papers based on these bitmap images.
In addition, as an example of the prior art to speed up the data transfer process, it is well-known that two independent buses, a system bus and a local bus, are provided and two bus controllers are provided between the system bus and the local bus. In regard to the data transferring apparatus, parallel processing is performed, that is, one bus controller accesses a main memory which is coupled to the system bus while the other bus controller accesses the local memory which is coupled to the local bus so that the data transfer process can be speeded up (For example, Japanese Patent No. 3251053).
In order to enhance the performance speed of liquid ejection in regard to the data transferring apparatus 10 of the conventional liquid ejecting apparatus configured as shown in FIG. 12, in other words, in order to further increase the recording speed in regard to the inkjet type recording apparatus, there are some obstacles as mentioned below.
First, since the compressed recording data is developed (extracted) by a program one byte each, it is impossible to process a great quantity of compressed data at high speed. If the microprocessor 11, which operates at high speed clock and has a high process capacity, is used, speeding up can be achieved, however, this causes such problems as the cost of the data transferring apparatus 10 gets extremely high if this expensive microprocessor 11 is mounted.
In addition, since both the data transfer to the RAM 12 and the data transfer from the RAM 12 are performed through the microprocessor 11, while the microprocessor 11 executes other data processes or calculations such as the microprocessor 11 fetches programs from the RAM 12, the data transfer might get into a waiting state, and thus the data transfer delay occurs, so that the data transfer at high speed can not be achieved.
Further, since the same route is used for both the access route from the microprocessor 11 to the RAM 12 via the system bus SB and the data transfer route from the RAM 12 to the recording head 62, the system bus SB is occupied while the microprocessor 11 accesses the RAM 12, so that the data transfer from the RAM 12 to the recording head 62 cannot be performed during that time. For this reason, the data transfer delay to the recording head 62 occurs, and thus the data transfer rate cannot be speeded up.
Further, in regard to the prior art disclosed in the Patent Document 1 described above, the compressed recording data is also developed (extracted) by a program one byte each, so that a great amount of compressed data cannot be developed at high speed. Therefore, in regard to the liquid ejecting apparatus such as the recording apparatus which executes recording by developing the compressed recording data transferred from an information processing apparatus and then transferring it to the recording head, the speed of ejecting liquid cannot be enhanced because the process to develop the compressed data is still slow though the data transfer process can be performed at high speed.